Method of dewaxing petroleum oil



De. 9, 1930. L. D. JoNEs 'I ETHOD OF D EWXING PETROLEUM'OIL Filed oct.7, 1925 INVENTOR ATTORNEY illy Patented Dec. 9, 1930 UNITED. STATESPATENT OFFICE-r` LEO D. JONES, AOF PHILADELPHIA, PENNSYLVANIA, ASSIGNORTO THE SHARPLES p SPECIALTY COMPANY, OF PHILADELPHIA, PENNSYLVANIA, ACORPORATION OFv DELAWARE Application led October 7, 1925.

My invention relates to a process of refining petroleum, andparticularly to the relining of that part of crude petroleum whichremains after gas, naphtha and burning oils have been distilled olf,such part of vthe petroleum, formerly called tar, being-herein referredto as long residuum of petroleum, and to the refining of certaindistillates of such' residuum. The term long residuum is intended tomean a still residue which in-l cludes a larger percentage of the crudeoil than would be contained in cylinder stock residuum made from thesame crude, and in general includes most of the lubricating content ofthe oil. v

It is an object of my invention -to provide a process whereby viscouslubricating oils of f low cold test are efciently and economicallyproduced from long residuum of petroleum anddistillates of such residuumthatA contain nonressable waX, contain oil of low speci c gravity andlow boiling point, and have a low flash point, e. g., a flash pointlower than 450 F. Oils that contain nonpressable Wax are oils from whichthe contained wax cannot be removed to a satisfactory degree in a singleoperation by precipitating the wax therein by chilling and then pressingthe 0il"through pervious material while the wax is held back by thepervious material, although a fraction may be taken from such oils bydistillation from which wax may be removed to a satisfactory degree bychilling and pressing. The wax in such' a fraction is light wax ('i. e.,of lower boiling point than other wax in the oil) and is the waxhereinafter referred to as light wax.

y,In the removal of non-pressable wax from oil it yhas formerly been thepractice to purify or decolorize the oil, before dewaxing it, bytreatment with acid or clay or both with the intended purpose ofrendering the removal of wax more complete and for the purpose ofdecolorizing the oil.

example oils having a dash point belowT 450- METHOD OF DEWAXINGPETROLEUM OIL This prac tice, wherein the oil was purified before beingdewaXed, worked satisfactorily with Serial No. 61,125.

F., difficulty was encountered in securing a desired degree of waxremoval as the light wax was not removed with the result that the coldtest of the oil was unsatisfactory and in fractionation of the dewaxedoil light wax' accumulated in the viscous neutral fraction giving thatproduct a higher cold test than the cold test of the viscousxfraction orbright stock residue although it is desirablev that the viscous neutralfraction have as low ,a cold test as possible. If o-il that containsnon-pressable wax is'purified by acid treatment or by clay treatment orby both of such treatments to such an extent that it meets commercialrequirements as to color and purity for a red or yellow oil, and if suchoil is in a diluted state either as a result of the presence of gas oilin it or as a result of the addition of naphtha, and'if the diluted oilis then chilled to precipitate the wax, then some of the wax may floaton the solution and therefore pass out with the oil in dewax- K lmay beeffected, in accordance with my invention, to a satisfactorily completedegree.. The separation of wax precipitated by dilution and chilling ofsuch wax-bearing oil may be carried out centrifugally. References tohard asphalt herein refer to .asphalt which is precipitated when the oilis eXtensively diluted with light naphtha and which if then compressedtogether forms a brittle cake and which impairs centrifugal dewax- I ingby producing hard accumulations within the centrifugal bowl. A.reference herein to impurities other than hard asphalt or' to impuritiesthat may readily'be removed by o moved by clay treatment have not asyet,

although decolorizing by clay treatment is old in lthe art, beenidentified chemically and it is not knownwhat other changes and removalsoccur in such decolorizing. It has been common practice to so purif thelong residuum or a distillate thereo prior to dewaxin and the abovedescribed difficulties obtain in the dewaxing. But, in accordance withthis invention a residuum or aY distillate thereof that is made fromwaxf bearing crude petroleum by steam distillay tion and merelysubstantially freed of hard asphalt, is' diluted and chilled and the waxis precipitated in a form in which it may be separated from the oil' bysubsidence, and

ysgreeo particularly by centrifugal separation. In other words 'I havediscovered that if oil containing light wax also contains a sufficientquantity of such impurities as are above mentioned, the light wax passesfrom the oil,'rparticularly in a centrifugal dewaxing operation, in thesame manner that heavywax present passes from the oil and in the samemanner that the wax passes from dec'olorizedsteam refined cylinderstock. In other words I have discovered that if oil contains light waxand also contains a sufficient quantity of such im urities as are abovementioned, chilling o the oil to a suiiiciently low degree will eiectsuch precipitation that the wax may be removed to a satisfactorilycomplete degree by a suitable wax'removing operation. I have alsodiscovered that a portion of the im urities that are present-pass fromthe oil'wit the waxes, that the ratio of impuritiessoA removed with thewax to the v'total impurities present before wax removal is at least aseat as the ratio of removed Wax to the original mixture of oil andl wax,and that the im urities that so pass out withthe waxes are t oseimpurities that are diiiicult to remove from the oil insubsequentpurification as with clay, in lthat it is these impurities which use upthe purifying property of a large portion of the cla that is used. `helong residuumv of some .petroleums -A naturally contains thoseimpurities which when present will insure a satisfactory de- `the longresiduum is 'dewaxed.

The long residuum of other petroleums will fbe found to contain a smallamount of asphalt. In other words the long residuum of some petroleumswill contain impurities other removal of non-pressable wax whenI thanthose that may readily be removed by clay treatment and which willinterfere with the operation of my process. Such excessive 4impuritiesinclude what is commonly termed hard asphalt. I have discovered that iflong residuum containing such impurities is given a mild acid treatmentlthat will leave in the long residuum such impurities as may be removedreadily by clay treatment, dewaxing of the resulting product issatisfactorily accomplished. Objectionable asphalt is aspedes thedischarge from the centrifugal bowl of the wax separated therein. Theidentificaand are (b) most readily (i. e., most economtion of theparticular impurities ofhoil that are referred to herein may be furtherfacilitated by a consideration of a long residuum of Waxbearing oilwhich is produced by steam distillation and which contains enough hardasphalt to produce an *appreciable` precipitate upon extensible dilutionof the residuum with light naphtha. While such asphalt might be removedby clay treatment of the residuum it is more economical, and it isusual, to remove such asphalt by mild acid treatment, but thi`impurities remaining after such mild acid treatment are removedeconomically, and for that reason readily, byclay treatment. The mildacid treatment effectively reduces the hard as halt content of theresiduum and althoug the operation is old the impurities removed in suchtreatment have 'not been chemically identified and its not known what'changes and removals occur other than reduction of the hard asphaltcontent. Therefore, im urities other than those that may readily i. e.,economically) be removed by clay treatment are those impurities whichare removed by the preliminary mild acid treatment and they include hardasphalt.

The long residuum of still other petroleums will be found to containmore asphalt than' can be economicallyI removed by acid treati ment forthe purpose of bringing the oil to a condition wherein dewaxing inaccordance with my processie satisfactorily carried out. I havediscovered that such long residuum may be brought to a condition whereinit may be dewaxed satisfactorily in accordance with my process, bydistillation that is so carried out that substantially all of thelubrieating content of the long residuum is dis- -tilled over withoutcracking and a sutlicient quantity of impurities ofthe character abovementioned is distilledover into the distillate.

lSuch distillation may becxsteam distillation llO at atmosphericpressure or .vacuum distillation or a combination of both. Thedistillate so produced is then treated in accordance with my invention.Distillates from pipe stills lhavealso been satisfactorily treated inac- 'dewaxing of the resulting product is satisfactorily accomplished inaccordance with my invention.

If the stock that is to be treated in accordance with my invention,regardless of Whether it is a distillate ora long residuum of petroleum,does not contain va sufiicient quantity of impurities to insure, asabove set forth, that non-pressable wax will be removed from the oil toa sufciently complete degree, impurities may be brought into the stockthat is to be deWaxed by blending such' distillate or long residuum thatis lacking inimpurities. with other products containing an excess otsuch impurities other than hard asphalt.

Regardless of Whether the product that is to be devvaxed contains thenecessary impurities naturally or by blending, and regardless of Whetherthe product that is to be deyvaxed has been brought to the propercondition by vacid treatment or by non-cracking distillation as abovedescribed, -the product that is to be dewaxed possesses` in anycasesubstantially the same characteristics. I A product that is to bedeWaxed and which contains enough of such impurities that dewaxing maybe satisfactorily effected in accordance with my invention Will beherein referredto as dewaxing stock regardless of Whether it wasobtained naturally, by blending, by .ac id treatment or' otherpurification or by distillation. n

In -carrying out my process crude oil 1s distilled Without cracking toremove the gas, naphtha and burning oil. If the long residuum thusobtainedor a. desired distillate thereof contains the impuritiesdesignated as desirable above, such stock then constitutes a de'waxingstock.` If the long residuum thus obtained or a desired vdistillatethereof does not contain the impurities designated above as desirable,such stock is brought bythe appropriate application of the steps of my-invention above set forth, to a condition wherein it constitutes adevvaxlng stock.

A feature of this invention is that by the steps leading toits formationor by blending,

a long residuum or 'a distillate is obtained or formed that containsimpurities that naturally occur in such distillates or residues and thatare most readily or economically removable by clay treatment, and thepresence of such impurities causes the wax as a whole that isprecipitated by chilling to be of such specific avity and such characteror degree' of plasticity that it may be removed by subsidence, andparticularly by centrifugal de- Waxing. While the impurities other thanhard asphalt may affect the specific gravity of the precipitated Waxthey nevertheless tend to cause precipitated Wax to be amor phous inform and they may therefore be said to constitute an amorphizing agent.

If the long residuum (such as long residuum of Cabin Creek crude-oil) ora' distillate thereof does not contain a sufficient concentration ofimpurities other than hard asphalt, to render the precipitated Waxreadily removable in a single operation, when that residuum ordistillate is produced in the most desirable Way, or if more extendeddis-y tillation for the purpose of carrying such impurities into thedevvaxingl stock is im! practical or would produce an oil of undesirableviscosity, impurities may be added by blending with the dewaxing stockoil products containing such impurities in excess, as above suggested,and either containing or free of wax. However, in some cases such iblending would be excessive and impair the efliciency of the dewaxingplant, as in the case of a distillate taken'for the purpose of.producing a non-viscous lubricating oil, and in such cases the processof my copending application Ser. No. 147,383,1iled November 9, 1926, maybe advantageously employed, that process involving the addition ofdistinctly amorphous Wax, or of petroleum products containing such Wax,either free of or containing amorphizing impurities.

In carrying out my invention the deWaX- ing stock, after its temperatureis reduced.; to about 120o F. if\-previous treatment has raised itstemperature above that point, is

diluted with about 55% to 65%, e. g., 62%, s of straight cut naphthahaving a .specific gravity of approximately 62 B. and the mixture isheated to about 100 F. to effect complete solution of the contained Wax.

-This mixture is then gradually cooled and.

`to P. T. Sharples, No. 1,232,104, the oil and Wax being continuouslyand separately discharged. The naphtha is removed from the dewaxedoiland the remaining product \is distillate, and, provided the dewaxingstock contains sufliciently viscous material, cylinder stockresldue.Both the non-viscous oil vand the viscous neutral oil will be of lightcolor 'andl will have a cold test below 25 F. and may be regarded asfinished lubrieating products. The cylinder stock will contain all ofthe impurities present in the dewaxing stock except those removed in thedewaxing operation'and will vbe of dark color.

If desired, this cylinder stock may be made into a bright stock by claytreatment and will then have a cold test of 20o F. or lower.

As one alternative the de-waxed oil, e. g., the oil discharged from thecentrifugemay be treated with or filtered through clay beforefractionation. This clay treatment or filtration may be carried outeither before or after the naphtha is removed. In this case" the productmay. then be fractionated, as by steam distillation. The products ofthis procedure will include vnon-viscous oil, viscous neutral oil and,provided the dewaxing stock contains sufficiently viscous material,bright stock residue. The non-viscous oil, viscous neutral oil and anybright stock residue will have the same properties as the similarproducts produced in accordance with the above described procedurewherein the clay treatment was limited tok the cylinder stock in whichall ofthe impurities were concentrated by distillation.

As` another alternative the oil discharged from the centrifugalseparator may be treated with or filtered through clay and -freed of thediluting naphtha by steam distillation, by whichever order of procedureis most convenient, and the resulting light colored low cold testproduct maybe used as afinished lubricant or as blending stock. "L

An important advantage of my invention resides in the fact that I amthereby enabled to more v completely remove non-pressable wax, includinglight 'wax that is in itself pressable, from oils of low flash test withthe result that I am enabled to dewax, particularly by a centrifugalprocess, all of .the lubricating content of crude petroleum and .toobtain not only lubricating oils of -low cold test but to obtain agreater proportionate yiel-d of such oil. Previous processes for thedewaxing of oils containing non-pressable wax have been of two kinds. Inone such process the wax was removed by filter pressing and in that casepreliminary cracking -to the mixture of Wax and oil.

treatment was necessary but that converted a large proportion of thelubricating content of the oil into non-lubricating products. In theother of such processes the amorphous wax was removed without change of)state by centrifugal dewa-Xing'of previously purified or decolorizedstock. I obtain substantially three times as much viscous neutral oil asis obtained by such processes wherein cracking distillation is restortedto for the purpose of bringing the wax into a form inl which it isremovable by a 'filter pressing'. Such previous centrifugal processeshave not atta-ined the improvement in cold test that results fromcentrifugally dewaXing the oil, in accordance with my invention, withoutpreviously decolorizing'the oil. Thus the final product attained by thepractice of my invention will have a cold test of 25 F. or lower eventhough the dewaxing stock was of low fiash test whereas previouscentrifugal rocesses when applied to dewaxing stock o low flash testproduced a final product having a cold test of 50 F. or higher.

Another important advantage of my invention resides in the fact thatwhen'wax isv removed from dewaxing stock before decolorization of thedewaxing stock, impurities that are of such character that they are themost difficult to remove from the oil will `pass from the oil when theoil is diluted and fraction, 15% to 30% in most'cases, of the originaldewaxing stock, and as above stated the ratio of impurities removed withthe wax to the total impurities of the dewaxing stock is at least asgreat as the ratio of wax But the wax may, without application ofdecolorizing treatment thereto, be converted and the total cost ofdecolorization is accordingly reduced. The separated" wax although itcontains the impurities left in it in the practice of my invention, maybe subjected to a cracking distillation andthe distillate thenfilter-pressed and sweated in order to produce paraffine, the colorbeing concentrated in the still bottoms. Or such separated wax may beused as a pressure still stock for the production of naphtha. If thedewaxed product is separately, i. e., after dewaxing, decolorized bytreatment with clay an advantage is gained in the fact that itis easierto pass the dewaxed product through the clay than it is to pass awax-containing product through the clay.

Another important advantage of my invention resides in the fact that myprocess is extremely fiexible with respect to the final a great 'varietyof straight run viscous neu-l tral oils-can be produced that have ayviderange of flash tests Yand that have viscosities up to as high as onethousand seconds Saybolt at 1000]?.

Another important advantage of my invention resides in the fact that indealing with Wax-bearing crudes containing a very large proportion ofasphalt a .distillate may be produced by distillation vwhich may besatisfactorily deWaXed by my process and from Which .may be obtainedcylinder stock or bright stock which cannot be obtained from thesecrudes by any other process and from which a much higher yield `ofviscous neutral can be obtained than by the customary process involvingcracking distillation of the crude and filter pressing to remove thewax.

From the foregoing it is apparent that lin the practice of my inventionlubricating oils of loW cold test and comprising an exceptionally largeproportion of viscous neutral oil and which are freed in the dewaxingoperation of impurities that are the most diiiicult to remove may beobtained from dewaXing stock consisting of long residuum or a distillatethat naturally contains certain impurities or that is prepared from longresiduum or distillate by blending with products that contain desiredimpurities or that areprepared by simple operations from long residuumor distillate containing asphalt.

In the practice of this invention one feature is that the oil is broughtto a condition which causes all of the Wax precipitated therein byreduction of temperature to be in that amorphous state in which it canbe removed from the oil by processes suitable to the removal 5071therefrom of precipitated amorphous Wax, in spite of the fact that theWax in the oil is of such character that if theV oil Were in some othercondition some of the Wax present would precipitate in crystalline form.That condition is arrived at in accordance With the' talline form. Inthe claims a statement that the precipitated Wax is in that amorphousstate in which it is removable by processes suitable to removal ofprecipitated amorphous wax means ,that all of the precipitated Wax is sohomogeneous and plastic that it is removable by such processes andremains in that condition until it is removed. Also, a

reference herein tov oil that contains crystalline Wax is intended as areference either to oil which contains an insufficient quantity ofamorphizing impurities to cause all of the precipitated Wax to be insuch amorphous state-or is free of such impurities and which will uponreduction of temperature produce a Wax precipitate of which some partiscrystalline; or to oil which may or may not contain a quantity of suchimpurities sufficient to cause all of the Wax precipitated therein byreduction of temperature to be in such amorc-l phous state but which iffirst freed of such impurities in Whole or in substantial part, as

by such treatment as Iwould bring the oil to commercially desired color,Will upon reduction of temperature produce a Wax precipitate of whichsome part is crystalline; or to oil which may or may not contain aquantity of such impurities suicient to cause all of the waxprecipitated therein by reduction of temperature to be in such amorphousstate but which by non-cracking distillation Will produce an initialdistillate that Will upon reduction of temperature produce a Waxprecipitate of which some part wis crystalline. In short, oil thatcontains crystalline Wax is oil from which Wax can be recovered that isin lnon-plastic crystals (even though the oil in-4 long residuumcontains so much asphalt that it is' desirable for economical reasons toproduce the devvaXing stock by distillation of the long residuum andsome hard asphalt or still residue is carried over into the distillate,it may be desirable to subject the distillate to a slight acid treatmentto eliminate such hard asphalt or still residue priorto dewaxing. WhileI prefer, in the practice of my invention to separate centrifugally theprecipitated Wax and the impurities that pass lout with it I do notlimit my invention to that method of separation in every case; and inthis conl\nection I consider that ani-tr known method of separatingprecipitated fw'aX from .the oil so long as non-pressable Wax andimpurities other than hard asphalt or such impurities as may readily beremoved by clay treatment gal dewaxing operations, such for example asthe use of an auxiliary or carrier liquid Within the centrifugalbowl.The chilling step of the dewaxing operation may also be modified inknownrespects.

The claims of this application are directed broadly to the ensuring ofthe presence in crystalline-waX-containin oil, prior to the deWa-xing ofsuch oil and y addition thereto or otherwise and for the urpose ofassisting` in dewaxing such' .crystal ine-WaxLcontaining oil, ofamorphizing ,impurities of petroleum, and specifically to the ensuringof the presence in such oil in such manner and for such purpose ofimpurities other than hard asphalt and which naturally occur inpetroleum oil and are commonly removed therefrom by extensive acidtreatment or by extensive clay treatment; and to the dewaxing of oilcontaining such impurities. My copending application Serial No. 147,383,filed November 8th, 1926 is directed broadly to the regulating of thecondition of crystalline-WaX-containing oil to the end that waxprecipitated therein may be separated therefrom by methods suitable tothe removal of precipitated amorphous wax, and broadly to the additionto crystalline-Wax-containing oil, for that purpose, of amorphizingsubstances, and specifically to the use "of such amorphizing substancesas amorphous Wax alone or amorphous Wax together'with'-amor phizingimpurities of which the use is claimed herein, and which are impuritiesother than hard asphalt which naturally occur in petroleum oil. Areference in the claims hereof to amorphizing impurities is intended asa reference to those impurities otherthan hard asphalt which naturallyoccur in petroleum oil and possess the property of causing crystallinewax toprecipitate in amorphous form, andis not intended to include waxthat occurs in petroleum.

Having thus describedmy invention, what I claim as new and desire tosecure by Letters Patent is: t l

1. The method of dewaxing the residuum remaining after the distillationof gas, naphtha and burning oils from Wax-bearing petroleum, whichcomprises subjecting the residuum to such acid treatment as willsubstantially remove hard asphalt therefrom While leaving therein otherimpurities' and thereby producing dewaxing stock, and then dewaxing thedewaxing stock Whilel it contains said other impurities by methodssuitable to the removal of precipitated amorphous wax. y

' 2. The method of dewaxing the residuum remaining after thedistillation of gas, naphtha and burning oil from wax bearing petroleum,which comprises substantially removing hard asphalt from the residuumWhile leaving other impurities and non-pressable Wax therein and therebyproducing de. Waxing stock, and then dewaxing the dewaxing stockcontaining said other impurities b methods suitable to the removal ofprecipitated amorphous Wax.

3.v In the treatment of petroleum, the method of dewaxing petroleumproducts containing crystalline wax and amorphous wax which comprisesforminga mixture of the oil containing crystalline wax and amorphous Waxwith amorphizing impurities causing Wax precipitated' from the mixtureby chill.-

ving to possess suiiicient plasticity and high enough specific gravityto be separable from the oil by centrifugal separation, -precipitat ingthe Wax by chilling and centrifugally separating the oil and wax.

4. In the refining of petroleum, the method of removing waxY frompetroleum oils containing crystallinewax and amorphous waxI whichcomprises forming a mixture of such oil and substancescommonly removedfrom petroleum oil by extensive acid treatment kor clay treatment,precipitating the Wax by chilling of such mixture and centrifugallyseparating the wax and oil.

y 5. In the refining of petroleum, the method of removing Wax frompetroleum oils `containing crystalline Wax and amorphous wax Whichcomprises so regulating the condition of the mixture of oil and wax withrespect to the amount and character of amorphizing impurities that thewax, upon precipitation by chilling y, after dilution,.is in a -state inwhich it is ,capable of being removed' from the oil by centrifugalseparation, recipitating the Wax by chilling, and centri ugallyseparating the wax and oil.

6. In the dewaxing of petroleum oil that contains crystalline wax andamorphous waxthe step comprising reducing the temperature of the Oil andremoving the wax which precipitates in amorphous form, while thel oilcontains those impurities which naturally occur in petroleum oil andwhich cause all of the wax precipitated in the oil by reduction oftemperature to be in an amorphous state.

be in that plastic state in which it is removable by processes suitableto the removal of precipitated amorphous Wax.

8. In the devvaxing of petroleum oil that contains amorphous Wax andalso crystalline Wax the steps comprising reducing the temperature ofthe oil While it contains amorphizing impurities that naturally occur inpetroleum oils Which cause all of the precipitated Wax to be inamorphous form, and centrifugally separating the precipitated Wax.

9. In the dewaxing of petroleum oil that contains amorphous Wax and alsocrystalline Wax, the steps comprising subjecting the oil to commonpurification continued to a point at which substantially the onlyimpurities that remain in the oil and affect precipitation of waxuponreduction of temperature thereof are those impurities which cause Waxprecipitated by reduction of temperature to be in amorphous form,reducing the temperature of the oil While it contains suiiicient of suchimpurities to cause all of the p recipitated Wax to be in amorphousform, and removing the 'precipitated Wax -by methods suitable to theremoval of precipitated amorphous wax. A

10. In the dewaxing of petroleum oil containing crystalline Wax,amorphous Wax and impurities that occur in petroleum yand impair `theprecipitation of Wax therein upon reduction of temperature thereof, thesteps comprising removing such impurities by common purificationmethods, then reducing the temperature of the oil While it containssuiicient amorphizing impurities that occur in petroleum oil to causeall of the Wax precipitated by such reduction of temperature to be inamorphous form, and removing the precipitated Wax by methods suitable tothe removal of precipitated amorphous Wax.

.11. In the deWaXing of petroleum oil that contains amorphous wax andcrystalline Wax, the steps comprising producing a mixture of such oiland impurities that naturally occur in petroleum oil and which cause Waxprecipitated from such oil to be all in an amorphous state, reducing thetemperature of the resultant mixture While it contains suiicientof suchimpurities to cau-se all Wax precipitated as a result of the reductionin temperature to be in an amorphous state, and removing theprecipitated wax by methods suitable to the removalof precipitatedamorphous wax.

12.. .In the dewaxing of petroleum oil that contains amorphous Wax andcrystalline wax, the steps comprising adding to such oil` in suchquantity as to cause all Wax precipitated therein by reduction oftemperature thereof to be amorphousin form, impurities that naturallyoccur in petroleum oil and which have the property of causing Waxprecipitated in such oil to be amorphous in form, reducing thetemperature of the resulting mixture and thereby precipitating Waxtherein in amorphous form, and removing the Wax by methods suitable'tothe" removal of precipitated amorphous wax.

13. In the treatment of "long residuum of petroleum remaining afterdistilling off gas, naphtha and burning oils from wax-containing crudepetroleum and containing amorphous wax, crystalline Wax, hard asphaltand other impurities naturally occurring in petroleum, the stepscomprising subjecting such long residuum to non-cracking distillationand thereby producing a distillate having a lower content of'hardasphalt than the long residuum and containing suiicient of such otherimpurities to cause all Wax precipitated in the distillateupon reduction'of temperature thereof, to be in amorphous form, and reducing thetemperature of the distillate and thereby yprecipitating Wax therein.

14. In the devva-Xing of petroleum oil that contains amorphous Wfaxjandcrystalline waxl and impurities which naturally occur in petroleum andare other than those impurities which occur in petroleum and cause waxprecipitated in the oil by reduction `of temperature to be in anamorphous state, the steps comprising subjecting such oil to such acid ltreatment as will substantially remove said impurities containedtherein, and then reducing the temperature of the resulting oil while lit contains, insuch quantities as to cause all wax precipitated thereinby reduction of temperature thereof 'to be in amorphous form, impuritiesthat naturally occur in petroleum oil and cause all of the Waxprecipitatedtherein by reduction of temperature to be in an'amorphousstate. l

15. In the dewaxing of petroleum'oil containing crystalline waX,amorphous wax, hard asphalt, and amorphizing impurities naturallyoccurring` in petroleum, the steps comprising subjecting such oil tonon-cracking distillation and thereby producing a distillate having alower content of hard asphalt than the original oil and containingsuflicient of said amorphizing impurities to cause all of the Waxprecipitated in the distillate upon reduction of temperature thereof tobe in amorphous `form, subjecting the distillate to mild acid treatmentto remove asphaltic impurities that interfere with precipitation of waxinthe distillate, and reducing the temperature of the acid-treateddistillate and" thereby precipitating` WaX therein. 1 16; In thedewaxing of petroleum oil con-l taining wax the steps comprisingreducing.`

the temperature, and thereby precipitating Wax therein, of petroleum oil which contains wax and is substantially free of hard asphalt andcontains, in a concentration suiicient to cause the oil tobe ofundesirably dark color and. insufficient to impair substantially theprecipitation of Wax therein by reduction of temperature .and in suchcbncentration that Wax precipitated therein by the reduction oftemperature is all removable from the oil by continuous centrifugalseparation, impurities that naturally occur in petroleum oil and 'areremovable therefrom by clay strong acid treatment or both of suchtreatments, and removing the precipitated Wax from the oil, togetherwith such of said impurities as accompany the wax removed from the oil,While the oil is at reduced temperature by methods suitable totheremoval of precipitated amorphous wax, and thereafter subjecting theresidual dewaxed oil to treatment suitable to the removal therefrom ofsaid impurities which remain therein to produce dewaxed oil of desiredlighter color.

In rtestimony whereof, I have signed my vname to this specification.

LEO D., JONES.

Las-armasV

